Electric elevator system



' June 24, 1930. s. B. GROSVENOR ELECTRIC ELEVATOR SYSTEM Filed Feb. 16,1923 5 h tsh 1 June 24, 1930. e. B. GROSVENOR 1,767,125

ELECTRIC ELEVATOR SYSTEM Filed Feb. 16, 1925 3 Sheets-Sheet 2 4 W/T/VEJSkw (B b INVENTOR wwkfw 5 g" I fl;

June 24, 1930, G. B. GROSVENOR I ELECTRIC ELEVATOR SYSTEM Filed Feb. 16,1923 3 Sheets-Sheet 5 .JTTURNEX Patented June 24, 1930 UNITED, STATESPATENT "OFFICE GRAHAM B. GBOSVENOR, OF CHICAGO, ILLINOIS, ASSIGNOR 1'0OTIS ELEVATOR COM- PANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OFNEW JERSEY ELECTRIC ELEVATOR SYSTEM Application alea February 1c, 1923.Serial No. 319,425.

proportion to the unbalanced load being lift ed'so that, in stopping,the effect of gravity 'is compensated for'by the kinetic energy in themoving parts. This means that the greater the unbalanced load beinglifted, the faster the elevator will run. This is very important inmaking the actual stop from low s eed as it makes it possibletodisconnect the elevator motor from its power supply at a fixeddistance from the landing and make an accurate stop.

The'object of my present invention is to provide means to compensate'forthe effect of gravity in stopping an elevator by causing the speed ofthe elevator to automatically be in some predetermined proportion to theunbalanced load being lifted, the means employed being applicable-tovarious methods of elevator control hitherto in use.

I accomplish this object by the use on the hoisting motor of a seriesfield winding which is' connected in the armature circuit an embodimentof my invention in a system.-

only during such time as the elevator is being retarded, and in such away that the flux, due to the series coils, is in the reverse sense tothat produced by the separately excited field coils, these latter beingalways su pliedlwith current in one direction.

order that my invention may be fully understood, it will be described inconnection with the accompanying drawings, in which I Figure 1 is awiring diagram illustrating utilizing a single'voltage supply and rh'eostatic control.

Figure 2 is a wiring diagram of a system in which a multivoltage powersupply with a proper control panel .isused according to my invention.

Figure 3 illustrates my invention in connection with a variable voltagecurrent supply as set forth in my copending appl ication Serial No.541,815, patented December 22, 1925, No. 1,566,399. Referring moreparticularly to the draw- 1ngs:-

Figure 1 is a wiring diagram for an elevator semi-automaticallycontrolled, utilizing a common form of rheost-atic control withmodifications. Emergency devices and safety features have been omittedin the wiring diagrams associated: with-this case, as theseappurtenances are too well known to require description and as in thenormal operation of the equipment these devices serve no purpose inconnection with the present invention.

To operate the elevator motor 2, a car switch 5 is provided in theelevator car and so wired that the car switch handleG must be moved toeither extreme position to cause the elevator to start after which carswitch handle 6 may be returned to neutral position at or near a landingprevious to the one at which it is desired to stop. The automaticswitches 7 and 8 will then automatically slow down and stop the elevatorlevel with the desired landing.

The elevator motor 2 has a constantly energized field winding 10.Suitable resistance 15 may be provided to cause the strength of thefield, due to winding 10, to be of a value that will give desired fullspeed. The field winding 10 and resistance 15 are preferably wound withconductors which will have a negligible temperature coeflicient so thatno variation in field strength will occur with change in temperatureduring operation. As change in the field strength will materially changethe speed, the field and other features of motor design are so designedthat variation in temperature or load will not materially affect thespeed. c

The object in having constant speed is for the purpose of fixing therate of retardation and the distance from the landing necessary toinitiate the slow-down to provide minis mum length of time forretardation, slow speed running and stopping.

Resistance 12 is protective resistance provided for field winding 10 inthe event of its power supply beingrinterrupted.

. means for automatically bringi This will require but one slow-downswitch 7 operating one slow-down contact for each direction of travel.In my copending application Serial No. 622,149 I have describled an eevator to rest under other con itions of floor hei ht or where the speedof the elevator is ifierent in one floor runs from its speed in two ormore floor runs.

The sto at the lan ng, re uires one contact a so for each direction otravel to stop theelevator.

Consider the elevator to be moved in the direction to the next adjacentlanding.v

u (Ear switch handle 6 is moved to the extreme left position so thatcontactor 16 covers contact finger points 17, 18 and 19. .A circuit isthen, completed from feeder 13 through fuse 20, lines 21 and 22, updirection switch magnet coil 23, line 24, tenninals F -F of travelingcable 9, line 25, contacts26 and -27 of the terminal automatic stopswitch, lines 28 and 29 contact finger 17, contactor 16, contact nger 19lme 30, terminals .BB of travehng cable 9, line 31, bottom contacts 32and 33 of the down direction switch, lines 34 and 35, fuse 36 to feeder14.

The up direction switch then closes contacts 37 and 38, 39 and 40, 41and 42, and 43 and 44. Contacts 45 and 46, and 47 and 48 are opened.

The brake magnet coil is ener 'zed by a circuit from feeder 13, througline 49 contacts 38 and 37, line 50, contacts 41 and 42, line 51, brakemagnet coil 3 .and rotective resistance 4, line 52 to feeder 14. heenergizing of brake magnet coil 3 releases the brak v The armature ofthe elevator motor re: vceives power from line 13, through contacts 38and 37, lines 53 and 54, armature winding of elevator motor 2, lines 55and 56 contacts 39 and 40, line 57, contacts 58 and 59, lines 60 and 61,starting resistance 62 to feeder 14. Due to the fact that contacts 58and 59 are in engagement and contacts 109 and 110 are separated, theseries field winding 11 is not connected in the elevator motor armaturecircuit.

A by-pass'resistance 67 at this time is connected across elevator motorarmature leads '66, resistance 67, line 68 ping switch 8, functioninonly 54, through line 53, contacts 37 and 38, line 49, line 13, line 63,contacts 64 and 65, line line 61, line 60 contacts 59 and 58, line 57,contacts 40 and 39, line 56 to lead 55.

A circuit is also completed for the magnet coils of automatic slow-downand stoppin switches 7 and 8 from feeder 13, throug line 49, contacts 38and '37, line 50, contacts '41 and 42, lines 51 and 69, fuse 70, line71,-

terminals H-H of travelin cable 9, line 72, magnet coils 73 and 74 o theautomatic slow-down and stoppin switches 7 and 8 respectively lines 75an '76, terminals C--C of the travel fuse 36 to,feeder 14.

Immediately upon the up direction switch closing, the fast speed magnetcoil is enerized and it closes its switch. The circuit is obtained fromfeeder 13 through line 49 ing cable 9, lines 77, 34 and 35,

contacts 38 and 37, line 50, contacts 41 and 42, line '51 to the right,fast speed magnet 0011 78, line 79, terminals A-A of the traveling cable9, line 80, contacts 81 and 82 of the terminal stop switch, lines 83 and84,

car switch contact finger 18, contactor 16 contact finger 19, line 30,terminals B-B of the traveling cable9 line 31, contacts 32 and 33 lines34 and 35, fuse 36 to feeder 14. The fast speed switch then closescontacts 85 and 86,'which completes a circuit for acceleratingmagnetcoil 88 from feeder 13, through fuse 20, line 21, contacts 85 and 86,line 87, accelerating magnet coil 88 to feeder 14'.

The accelerating magnet then closes contacts in pairs as follows :89 and90, 91 and 92, 93 and 94, 95 and 96 and 97 and, 98 which serve toshort-circuit starting resist-' anoe 62 in successive steps. Immediatelyupon the first section of resistance'62 being short-circuited bycontacts 89 and 90, the bypass resistance 67 is open-circuited by thecontacts 64 and 65 opening.

The'elevator will now run at full speed. A circuit is establishedthrough the compensating switch magnet coil 107 from feeder 13 throughline 49, contacts 38 and 37, line 50, contacts 41 and 42, lines 51 and69, fuse 70, line 71, terminals H-H of the traveling cable 9, lines 72and 99, resistance 100, line 101, terminals E'E of the traveling cable9, line 102, contacts'44 and 43, line 103, contacts 104 and 105, line106, compen sating switch magnetcoil 107, lines 108, 34 and 35, fuse 36to feeder 14. The last step of the accelerating magnet opens contacts104 and 105 hrs this circuit after full acceleration. The value of theresistance is such, however, that magnet 107 was not suflicientlyenergized to close the contacts that series field winding 11 is stillnot connected in circuit.

It was shown that when contactor 16 of the car switch bridged thecontact fingers 17, 18 and 19, the elevator was brought up to fullspeed. By centering the car switch handle 6, contactor 16 uncoversfingers 17, 18 and 19. Contact fingers 19 and 17 and 19 and 18 are stillbridged by resistances which enable the direction and fast speedswitches respectively to remain closed after the air gaps of the coreshave been reduced by the closing of the switches. The circuit, bridgingcontact fingers 19 and 17 to hold in the u direction switch, extendsfrom contact nger 19 through lines 111 and 115, contacts 116 and 117 onthe automatic stopping switch, resistance 118, lines 28 and 29 tocontact finger 17. For the fast speed switch, the circuit is obtainedfrom car switch finger 19 through line 111, contacts 112 and 113 on theautomatic slow-down switch, resistance 114, lines 83 and 84 to contactfinger 18.

The elevator proceeds to a point approximately midway between landingswhere the magnet core of slow-down switch 7 is attracted by thestationary armature 119, which is mounted in the hatchway, openingcontacts 112 and 113, thus releasing the fast speed switch bydeenergizing magnet coil 78 and opening fast speed contacts85 and 86.

The opening of contacts 85 and 86 deenergizes the accelerating magnet 88which inserts resistance 62 in series with the elevator motor' armature,resistance 67 in parallel with the elevator motor armature and closescontacts 104 and 105.

Automatic slow-down switch 7 has also closed contacts 121 and" 122,which shortcircuit resistance 100 in series -with com- 'pensating switchmagnet coil 107.' The compensating switch is, therefore, closed, closingcontacts 109 and110 and opening contacts 58 and 59.

When theautomatic slow down switch is beyond the range of'armature 119,contacts 121 and 122 again'open but thecircuit remains establishedthrough resistance 100 and sufiicient current flows to keep compensatingswitch magnet coil 107 energized sufficiently to keep its switch closed.

By t e opening ofcontacts 58 and 59 and the closing of contacts 109 and110, the armature current of the elevator motor is caused to flowthrough the's'eries field wind-v ing 11 which is; so connected as to bein opposition to the shunt field winding when the-motor 2 is drawingcurrent from the line, but since, in slowing down, the elevator motorwill deliver energy, the series winding 11 will increasethe fieldstrength, thereby increasing the retarding action. When slow speed isreached, differential compounding will be obtained, the demand for powerby the elevator motor will be determined by its load so that withincreasin loads the speed will be increased and with decreasing loadsthe speed will be decreased. The extremes, of course, are full load upand down. In the first case, differential compounding will cause anincrease of speed while in the second case the elevator motor willdeliver power since it is being driven by gravity, thereby reversing thecurrent in the series field winding which results in cumulativecompounding. field' winding here is for the purpose of slowing down andcompensating for gravity at slow speeds preparatory to stopping bycausing the kinetic energy of the moving parts for various loads "to beinversely to the action of gravity. By properly proportioning the serieswinding and the shunt winding, a condition is reached that .will causethe elevator to stop in the same distance, regardless of load.

When the elevator nearly reaches the landing, the magnet core of switch8 is opposite stationary armature 120 and is attracted by it, openingcontacts 116 and 117, releasing the up direction switch which interruptscur- The use of the series.

rent to the elevator motor armature, and applies the brake while theclosing of bottom contacts on the up direction switch, connects dynamicstopping resistance 123 across the elevator motor armature leads 54 and55, through line 127, contacts 47 and 48, resistance 123, contacts 124and 125, and line 126.

Figure 2 is an adaptation of similar control as in Figure 1 for use onmulti-voltage' system of supply mains where four sources of supply ofelectrical energy are furnished connected in series to permit four equalsteps of voltage; for example a battery of storage cells providing atotal E. M. F. of 240 volts with three intermediate and two externalsupply lines. These lines may be numbered 128, 129, 130, 131, 132 and soconnected as to obtain 60 volts or any multiple of 60 volts with amaximum of 240 volts. The feeders are so arranged that 128 and 129 havea difference in potential of 60 volts, 128 and 130 have 120 volts, 128and 131 have 180 volts and 128 and 132 a difference in potential of 240volts. This system is not new and is well known in the art.

-The general arrangement of control from the up direction switch magnetcoil circuit, which switch in turn com letes various supplementarycircuits and en the circuit for the magnet coils of the speed oraccelerating switches, which in turn perform their rebut is onlyconnected in during slowing down and stopping. On starting up, contactor133 of car switch 5 bridges contacts 134, 135 and 136 and a circuit isobtained throu h the up direction switch magnet coil as follows:- fromfeeder 128 through fuse 137, lines 138 and 139, up direction switchmagnet coil 140, i

line 141, terminal stop switch contacts 142 and 143, lines 144 and 145,contact finger 134, contactor 133, contact finger 136, lines 152 and151, contacts 153 and 154, lines 155 and up' 156, fuse 157, line 158right to feeder 132.

When returning car switch handle to neutral contact fingers 134 and 136are still bridged through line 152, right lines 151 and 150, contacts149 and 148, line 147, re-' sistance 146, line 145 to contact finger134.

The resistance 146 is of such value that the up direction switch willremain in afterbein closed.

e up direction switch closes contacts 159 and 160, 161 and 162, 163 and164 and 165' and 166, and oge hns contacts 167 and 168 and 169 and 170.

e brake magnet coil is now energized from line 128 through line 171,contacts. 160 and 159, line 172, contacts 164 r and 163, line 173 left,brake magnet coil 3 and protective resistance 4, lines 175 and 158 tofeeder 132. The brake is now lifted and the elevator will run on lowspeed with 60 Y volts available for the elevator motor armature fromfeeders 128 and 129 as follows from feeder 128 through line 171,contacts 160 and 159, line 176, armature-winding of elevator motor 2,lines 179 and 180, contacts 161 and 162, line 181, resistance 177, line178, contacts 182 and 183, lines 184 and 185,

contacts 186 and 187, line 188, contacts 189 and 190 to feeder 129.

By-pass resistance 193'is also across the armature at this time fromarmature line 179 through lines 180, 191. and 192, resistance 193, line194, contacts 195 and 196,

' lines 197 and 198 to armature line 176.,

Auxiliary fast speed switch then closes as its magnet coil 199 isenergized through a,

1 The auxiliary-fast speed switch closes contacts 204 and205,'short-circuiting armature series resistamTe 177 and opens contacts195 and 196, disconnecting by-pass resistance 193. Contacts 206 an areclosed preparatory to getting higher speed. The elevator motor is nowrunning at low speed 'with60 volts across its armature terminals and"without series or by-pass resistance. Automatically, however, theelevator continuesup to full speed. The successive accelerating stepsare obtained by the closing ofswitches by magnet coils 208, 209 and 210,a circuit forthese coils being obtained primarily from the car switch,and next by the closin of contacts 206 and 207 bythe auxiliary ast speedswitch. Magnet coils 208, 209 and 210 are electrically interlocked bymeans of auxiliary contacts, for sequence in operation when closingtheir respectiveswitches, all receiving power from the same SOlllCB.

The energization for magnet coil 208 is obtained from feeder 128 throughfuse 137, line 211, magnet .coil 208, line 212, contacts 207 and206,line 213 contacts 214 and 215v of the terminal stopping. switch, line216, car switch contact finger 135, contactor 133, contact finger 136,lines 152 and 151, contacts 153 and 154, lin; 155 up, fuse 157, line 158to feeder 132.

circuit extends from contact 136 through lines 152 and 151, contacts 220and 219, line 218, resistance 217 to contact finger 135. The resistance217 is of such a value that the switches operated by magnet coils 208,209 and 210 will remain in after being closed, but they will not pull inif open.

The closing of the switchby the energizing of magnet coil208, raises thepotential across the elevator motor armature from to 120 volts asfollows :The contacts coning sequence. Contacts 221 and 222 closecompleting a circuit from feeder 129 throu h contacts 190 and 189, line188, contacts 1 7 and 186', line 185, resitanee 232, line 231, contacts222 and 221, line 225, contacts 226 and 227,, line 228, contacts 229 and230, to feeder 130 connecting resistance 232 across 60 volts potential.Contacts 186 and 187 open, connecting resistance 233 in series withresistance 232, the line 184 instead of being connected direct to feeder129 is now obtaining power from a point between resistances 232 and 233connected in series across feeders 129 and 130. Contacts 223 and 224then close-short-circuiting resistance 232. The line 184 feeding thearmature circuit is new direct connected to feeder 130 of the 120 voltlevel and resistance 233 is goiiggcted directly across the feeders 129an Contacts 189 and 190 then open which dis- With car switch handle inneutral, this trolled by this switch operate in the followconnectsresist ance 233, and the armature of the elevator motor is then on the120 volt level and the transfer resistances 232 and 233 areopen-circuited.

Auxiliary contacts 234 and 235'and 236 and 237 on the switch controlledby magnet coil 208 are closed at this time. The closing of contacts 234and 235 short-circuits contacts 201 and 202, controlled by the auxiliaryfast speed retarding magnet coil 242, through lines 243, 156 and 203 and442 and 200.

The purpose offthis arrangement is to' prevent auxiliary fast speedmagnet coil 199 from being deenergized and thus effecting the insertionof series resistance 177 and 'by-pass'resistance 193 in the armaturecircuit at other than low speed preparatory to stopping. Magnet coil 2420 the auxiliary fast speed retarding switch is connected across thearmature terminals of the elevator motor 2 and so adjusted as to opencontacts.

.201 and 202 at a voltage above 60 volts on an increasing voltage and tobe of sufficient strength to hold the contacts open, because of thedecreased air gap of the magnet cores, at 60 volts on a decreasingvoltage.

Therefore, when accelerating, magnet coil 242 will not cause contacts201 and 202 to open until after magnet coil 208 of the firstaccelerating switch has closed contacts 234 and 235. At such-time, thevoltage at the armature terminals will be 120. Then when slowing downpreparatory to stopping the release of the switches controlled by coil208 .will open contacts 234 and 235 and since contacts 201 and 202 areopen the auxiliary fast speed magnet coil 199 will be deenergized andits switch will be released to connect series resistance 17 7 andby-passre- Contacts 236 and 237 are also closed by the energizing of the magnetcoil 208 and a circuit is completed to cause the second step ofacceleration by magnet coil 209 obtaining its'feed from wire 213 in thesame manner as coil 208 but branching off at the control panel throughline 244, contacts 237 and 236, line 245, coil 209, line 211, fuse 137to feeder 128. The second step of acceleration brings the elevatorarmature voltage up to 180 increasing this voltage 60 volts inv the samemanner as the switch controlled by magnet coil 208.

Auxiliary contacts 238 and 239, closed by the energizing of coil 209,complete the circuit for magnet coil 210 and the armature .voltage isincreased another 60 volts in the same manner, at which time thearmature of the elevator motor will'be across the two outside feeders128 and 132 having a differswitch 7 passes its respective stationaryarmature 119. The circuits of the magnet coils of. both the automaticslow-down switch 7 and automatic stopping switch 8 are closed fromfeeder 128 through line 171,

contacts 160 and 159, line 172, contacts 164 and 163, lines 174 and 246,magnet coils 247 and 248, line 249, fuse 157, line 158 to feeder 132.The magnet core of the automatic slow-down switch 7 is attracted by thestationary armature and contacts 219 and 220 open, which causes theopening of all circuits for magnet coils 208, 209 and 210 which willrelease their switches bringing the elevator motor armature voltage downto 60 volts. These switches are mechanically interlocked or if desiredmay be electrically interlocked so that the releasing will be in thereverse sequence to that in which the switches were coil 208 releasesthe auxiliary fast speed switch by deenergizing magnet coil 199 andseries and by-pass resistances 177 and 193 respectively are. connectedin the armature circuit of the elevator motor 2.

At the timethat the slow-down switch 7 the low speed to be inversely tothe load im posed on the elevator'motor. The circuit for compensatingswitch magnet coil 252 is from feeder 128 through. line 171, contacts160 and 159, line 172, contacts 164 and 163, lines 174, 246 and 452,contacts 251 and 250, lines 253 and 254, contacts 166 and 165, lines 255and 256, contacts 241 and 240, line 257, magnet coil 252, lines 258 and156, fuse 157, line 158 to feeder 132. The deenergizing of magnet coil252 causes contacts "260 and 261 to close and contacts 183 and 182 to 0en. The

closing of contacts 260 and 261 s unts the tact 183. The opening ofcontacts 183 and 182 then interposed the series field winding in theline providin for the compounding desired. The series; eld winding isnot provided with an adjustable shunt as it maybe so diesigned as togive the compounding de- SITE 1 I Not only can an extremely low averaarmature o ened, releasing the up direction switch,

Thle elevator will now be running at slow s preparato to sto in T eotentiifi available fo r the ele ftorgarmatuig will be volts and theseries field'winding 11 and series resistance 177 will be in series withthe'armature windin By-pass resistance 193 will be across t e armaturewinding. speed be obtained-but the series field win ing will ermithigher speeds lifting the loads than that obtained when lowering theloads. The stopsing of, the elevator with this method of spec regulationat low speeds will be accomplished in a very short distance, lendingitself to extreme accuracy of stopping at floor landings by automaticmeans.

When the elevator platform is nearly at the landin the core of theautomatic stopping switc 8 is attractedby its stationary 120 andcontacts 148 and 149 are t us interrupting ower to the elevator motorarmature, bra 'e magnet coil and other operating circuits. Dynamicstopping resistance 265 is connected across the elevator motor armaturethrough contacts 168 and 167 and contacts 266 and 267, lines 198, 172and 176, and lines 191, 180 and 179 respectively. Y

InFigure 3, the motor generator set 268 consists of a shunt wound motor279 driving a generator 274 obtainin power from the ower feeders throughmain line switch 269.

he separately excited field 273 of the genera'tor 274 is connectedacross the ower su ply feeders 270 and 271 from eeder 2 0 line 275,

through line 277, resistance 276 field winding 273, .line 272 to feeder271.

Protective resistance 278 is connected across the shunt field windingfrom line 275 to feeder 271, to line 272.

The separately excited field 10, and its rotective resistance 12,' ofelevator motor 2 1S connected permanently across feeders 270 and 271through lines 280 and 281.

The elevator may be started in the up direction by moving car switchhandle 6 to the extreme left hand position. After 0 erating circuitshavebeen established by th car switch 5, car switch handle 6 may bereturned. to neutral position and the elevator will continue toaccelerate to a point midway betweenthe landing from which it hasstarted and the adjacent landing above.

-At this midway point, the slow-down will be initiated, and the seriesfield winding 11 will be connected in series with the elevator motorarmature, being accumulative or differential depending upon the flow ofvcurrent through its winding. By connecting the series field winding 11in a manner that is' commonly known as difierentially compounded, theelevator inotor will be accumulatively compounded when delivering energyare completed by contactor 282 bridging e remeans and differentiallycompounded when receiving energy.

his permits series field winding 11 to assist in slowing down theelevator motor and at slow speed to increase the speed with load tocounteract the effect of gravity b the change in kinetic energy due tospec add to that of field winding 10 thereby increasing the fieldstrength and decreasing the speed.

Stopping is accomplished by interrupting current to the elevator motorarmature, applying a dynamic stopping resistance across the elevatormotor armature and applying the brake. By .holding car switch han le 6in its extreme position, the elevator will continue to run at fullspeed, after it has accelerated, until the operator centers handle 6,when it will sto at the next landing beyond the first s ow-down switchit encounters. 1

The circuits established by moving handle 6 over are those for thelcoilsof the up direction and fast speed switches and they contact fingerpoints 283, 284 and 285. T

ective paths are from contact point 285 iiirou h contactor 282 'tocontact point 283 and from contact point 285 through contactor 282 tocontact,point 284. The bridging of these contactpoints is done forthepurpose of short-cii puiting resistance 286, the circuits extendingfrom contact finger 283 through line 287, resistancef286, line 288, Icontacts 299 and 300, lines 301, 302 and 303 for the up direction switchma et circuit; and for the purpose of short-clrcuiting resistance 307from contact finger 284, through lines 305 and 306, resistance 307, line308, contacts 309 and 310, lines 311, 302 and 303 4 to contact finger285. The short-circuiting of resistances 286 and 307 increases thecurrent in these circuits, ermittin these magnet controlled switc es toc ose. These switches having closed remain closed after the car switchhandle has been returned to neutral, the magnet coil circuits thenextending through resistances 286 and 307 and contacts 299 and 300 andcontacts 309 and 310.

Consider now the elevator tobe run one floor in the up direction and tobe stopped automatically at the adjacent landing Car switch handle 6 ismoved to the extreme left hand position and returned to neutral positionimmediatel Circuits from start cuit extending from feeder 270 throughfuse 312, lines 313, 314 and 315, up direction switch magnet coil 316,line 317, contacts 318 and 319 of the terminal stopping switch, lines320 and 287, contact .finger point 283, contactor 282, contact fingerpoint 285, lines 303 and 304, contacts-321 and322, line 323,

.fuse 324 to feeder27 1. When car switch handle 6 is returned toneutral, thiscircuit takes the path from line 320, through resistance286, line 288, automatic stopping switch contacts 299 and 300, lines 301and 302 and-back on 304 as before. The up direction switch is closed bythe magnet coil 316, which closes contacts 325 and 326, 327 and 328, 329and 330 and 331 and 332 and opens contacts 333 and 334 and 335 and 336.

The closing of contacts 325 and 326 permits and 325,1ine 337, brakemagnet coil 3 and protective resistance 4, line 338 to feeder 271. Thebrake magnet coil 3 being energized, releases the brake shoes from thebrake wheel permitting the elevator motor armature to rotate. Thearmature of the elevator motor receives power from generator 274, thecircuit being from the generator armature through line 339, contacts 330and 329, lines 340 and 341, armature winding of elevator motor 2, lines342, 343 and 344, contacts 331 and 332, line 345, contacts 346 and 347.line 348 and back to generator armature.

The elevator motor is now at slow speed but as a circuit isestablishedfor the fast speed ma net coil, the fast speed switch closes animmediate acceleration is obtained. This circuit extends from feeder270, through fuse 312, line 313, contacts 326 and 325, lines 337 and349, fast speed magnet coil 350, line 351, contacts 352 and 353 of theterminal stopping switch, lines 354 and 305, contact finger 284,contactor 282,

.contact finger 285, lines 303 and 304, contacts 321 and 322, line 323,fuse 324 to feeder 271. Upon restoring car switch handle 6 to neutralposition, a self-holding circuit for the fast speed magnet coil is stillestablished ance 276 in series with the field winding 273 ofthegenerator 274. The voltage of generator 274 buildsup to fullpotential, accelerating elevator motor 2, the armature of which issupplied with power from generator 274. The opening of contacts 357 andhas no function at this time.

' The magnet coils 259 and 260 which are in parallel, are utilized toenergize the automatic stopping switch 8 and the automatic slow-downswitch 7. The circuit for these magnet coils is obtained from feeder 270through fuse 312, line'313, contacts 326 and 325, lines 337 and 361,magnet coils 359 and 360, lines 362, 363 and 323, fuse 324 to feeder271. Upon reaching a point midway 'be tween the adjacent floorsconstituting the run, the core of switch 7 is attracted by stationaryarmature 364, thereby opening contacts 309 and 310 and initiating theslowdown by deenergizing fast speed magnet coil 350 and releasing itsswitch thus inserting resistance 276 in the circuit of field winding 273of the generator 274 and the voltage of generator 274 decreases withdecrease of field strength. Switch 7 also closes contacts 365 and 366completing a circuit from feeder 27 0 through fuse 312, line 313,contacts 326 and 325, lines 337, 361 and 367, contacts 366 and 365, line368, contacts 327 and 328,1ines 369 and 370, contacts 357 and 358 whichare now closed by the release of the fast speed switch, line 371,compensating switch magnet coil 372, lines 363 and 323, fuse 324 tofeeder 271.

' After switch 7 has passed beyond the range of armature 364, thecircuit established will still remain effective by the use of resistance373 connected across contacts 366 and 365. The resistance 373 is usedfor the purpose of permitting magnet coil 372 to hold in the switchcontrolled once it has closed, but will prevent the magnet coil 372 fromoperating its switch when it is open.

The com ensating switch closes contacts 374 and 3 5, which connectsseries field windin 11 of motor 2 across contacts 346 and 34 throughlines 375 and 376 after which contacts 346 and 347 are opened,connecting the series field winding into the armature circuit of theelevator motor 2. This permits the series field winding to assist in theretardation and compensate for gravity by a change in kinetic energy.

The elevator approaches low speed suitable for the load after which theelevator will be nearly to the landing at which it is desired to stop.At this time the core of switch 8 will be attracted'by armature 377thereby opening contacts 299 and 300 which will open the up directionswitch magnet coil circuit releasing the switch controlled by it tointerrupt power to the elevator motor armature, deenergize .brake magnetcoil 3 permitting the brake to apply and connect dynamic stoppingresistance 378" across arswitch other operating circuits that wereclosed during the starting up are opened and contacts and circuits onceagain are as shown in the wiring diagram Figure 3.

The operation and circuits have been describedin connection with thedrawings for the up direction of travel only. It will be understood thatdown direction is obtained e circuits are all shown but not desc'riMagnetic slow-down and stopping switches are shown diagrammatically andmay be of any suitable construction but the preferred form is thesubject of my copending ap 1ication Serial No. 619,426. It will be unerstood' that there are stationary armatures for these switches at eachfloor, althou h those for but one floor are shown in t e drawings, inorder, to simplify the diagrams. It is also apparent that switchesoperated mechanically b cams in the hatch may be used, if desire Othermodifications of control may be made without departing from the spiritof my invention.

I claim 1. An electric elevator system comprisin a hoisting motor, aseparately excited winding winding fie d winding for said motor, aseriesfield for said motor, and means for connecting said series field windingin the armature circuit of said motor only during periods ofretardation.

2. An electric elevator system comprising,

a hoisting motor, a separately excited field or said motor, a-seriesfield winding for said motor, and means for connecting said series fieldwindin in the'armature circuit of said motor only uring periods ofretardation and in such manner that its magnetizing force op oses thatdue to the separately excited fie d winding when the motor is receivinenergy.

3. An electric e evator system comprising, a hoistin motor, a separatelyexcited field winding or said motor, a series field winding for saidmotor, and means for connecting said series field windin in the armaturecircuit of said motor only uring periods of retardation and in suchmanner as to assist the separately excited field winding while the motoris deliverin ener y and to oppose the separately excite fiel windingwhile the motor is receiving energy.

4. An electric elevator system comprising, a hoisting motor, aseparately excited field winding or said motor, a series field windingfor said motor disconnected during periods of acceleration and fullspeed running, and means'for conne ting saidseries car switch handle 6to the right.

ed. ing for said motor disconnected during ,pe-

6. An electric elevator system comprisin a hoisting motor, a separatelyexcited fie d winding for said motor, a series field wind riods ofacceleration and'full speed running and means for causing theretardation oi said motor, saidmeans'includin means for connecting saidseries field'win ing inthe armature circuit of said motor.

7. An electric elevator systemcomprising, '1

a hoisting motor, a separately excited field winding for said motor, aseries field winding for said motor disconnected during periods ofacceleration and full s ed running, and means for connecting said seriesfield winding in the armature circuit of said motor during periods ofretardation and in such manner as to assist the separatel excited fieldwinding while the motor is eliveringenergy and tooppose the separatelyexcited fieldwinding while the motor is receiving energy. v

8. An electric elevator system comprising, a hoisting motor, aseparately excited fie d winding for said motor, a series field windingfor said motor, and means for introduc- I ing said series field windinginto the arma ing for said motor, and means for introducing said seriesfield winding into the arma-' ture circuit of the motor during periodsof retardation in such manner that it assists the separately excitedfield winding while the motor is delivering energy and opposes theseparately excited field winding while.

the motor is receiving energy.

10. An electric elevator system comprising, a hoisting motor-Ea?separately excited field winding for said is receiving ener regard essofthe direction of rotation o the motor, and means for introducing saidseries field winding into the motor armature circuit during retardation.

11. An electric elevator system comprising in combination, a hoistingmotor, a sepmotor, a series field winding for said motor for opposin thesap-- arately excited field windin whilet e motor aratel excited fieldfor said motor, a series separately excited field while said motor isdelivering current and to oppose the sepa rately excited field whilesaid motor is drawing current from the line only during periods, ofretardation and subsequent slowspeed running.

12. An electric elevator system comprising in combination, a hoistingmotor, a separatel excited field for said motor, a series field or saidmotor, and means for connecting said series field in the armaturecircuit of said motor during periods of retardation and subsequentslow-speed running and for disconnectmg. said serles field from thearmature circuit, during periods of acceleration and full-speed running.

13. An electric elevator system comprising in combination, ahoisting'motor, a separately excited field for said motor, and a seriesfield for said motor, means for automatically connecting said seriesfield in the armature circuit of said motor during periods ofretardation and subsequent slowspeed running and for automaticallydisconnecting said series field from the armature circuit during periodsof acceleration and full-speed runnmg.

14. An electric elevator system comprising in combination a hoistingmotor, a separatelyexcited field for said motor, a series field for saidmotor, and means for connecting said series field in the armaturecircuit of said motor during periods of retardation and subsequentslow-speed running so as to assist the separately excited field whilesaid motor is delivering current and to opposethe separately excitedfield while said motor is drawing current from the line and fordisconnecting said series field from the armature circuit' accelerationand full-s%ed runnm GRAHAM enosv NOR.

of said motor during periods of

